1. Field of the Invention
The invention relates to a machining unit on a machine tool, especially a universal milling and drilling machine, an adapter unit insertable into the machine work spindle with plug-in connections connected by lines to supplies of working media and mating plugs for releasably connecting the adapter unit to the working-media supplies.
2. Discussion of the Related Art
For the purpose of high-speed machining with spindles rotating, for example, at 30,000 rpm or more, even on conventional milling and drilling machines, there are known separate adapter units comprising a rapidly rotating additional spindle which can be inserted in the normal spindles of milling and drilling machines when needed. The adapter units can be supplied with working media such as coolants, lubricants, hydraulic fluid, compressed air or the like via a conventional plug connector which can be coupled between the adapter unit and the spindle casing. These plug-in units, however, must remain firmly connected even under the loads occurring during machining, so as to avoid disturbances in operation caused by leaks or undesired breaks in the line.
A primary purpose of the invention is to provide a machining unit of the type identified above for securely connecting the plug connections on the spindle casing to the mating connections on the adapter unit. To this end, according to the invention, a clamping device for releasably holding the plug-in connections and mating connections in the coupled position is disposed on at least one of the two connecting parts.
By means of the preferred embodiment of the invention, the plug-in connections for connecting the adapter unit to a supply of working medium, which can be automatically coupled together when an adapter unit is inserted in the working spindle of a machine tool, can remain securely interconnected even during the machining operation. This ensures that the adapter unit receives a reliable, interference-free supply, for example, of coolant for cooling an additional drive, hydraulic fluid for actuating clamping devices, compressed air for cleaning clamping cones on an additional spindle, cooling lubricants for supplying to the machining station and the like.
In a particularly advantageous embodiment, for example, the clamping device can, for example, be a clamping unit disposed on the first connecting part for releasably holding a tightening pin disposed on the second connecting part. The clamping unit can be constructed like an automatic tool tension jack incorporated in the working spindle, by means of which a clamping cone disposed on the adapter unit is clamped in the working spindle. By this means, for example, the hydraulic actuating means of the clamping unit for releasing the connecting parts can be coordinated in simple manner with a corresponding actuating means of the tool tightening jack for releasing the clamping cone, thus simplifying the control system.
In another advantageous embodiment a groove is disposed on one of the two connecting parts for engagement, sealed by a sealing ring, of a web provided on the other connecting part. By this means, when the two connecting parts are connected by the clamping device, the plug connector can be protected from being soiled by machining residues or cooling lubricant accumulating during the machining operation.